Very large layer 2 (VLL2) networking technology has been implemented in data center (DC) networks. VLL2 networking technologies such as the transparent interconnection of lots of links (TRILL) and the shortest path bridging (SPB) have been developed and have been standardized by different standards organizations. TRILL protocol is a layer-two network technology defined by Internet Engineering Task Force (IETF). The TRILL protocol introduces Intermediate System-to-Intermediate System (IS-IS) adopting layer-three routing technology into a layer-two network. Accordingly, the simplicity and flexibility of layer-two network may be combined with the stability, extensibility and high-performance of layer-three network.